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Lena Bell 2022-07-12 Answered
If sin 2 x + sin 2 2 x + sin 2 3 x = 1, what does cos 2 x + cos 2 2 x + cos 2 3 x equal?
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Answers (2)

Darrell Valencia
Answered 2022-07-13 Author has 10 answers
You know that
sin 2 x + sin 2 2 x + sin 2 3 x = 1 ( Eq. 1 )
Notice that
sin 2 x + cos 2 x = 1 sin 2 x = 1 cos 2 x
Substituting the identity in Equation (1):
sin 2 x 1 cos 2 x + sin 2 2 x 1 cos 2 2 x + sin 2 3 x 1 cos 2 3 x = 1 1 cos 2 x + 1 cos 2 2 x + 1 cos 2 3 x = 1 3 ( cos 2 x + cos 2 2 x + cos 2 3 x ) = 1 2 = cos 2 x + cos 2 2 x + cos 2 3 x
Therefore:
cos 2 x + cos 2 2 x + cos 2 3 x = 2
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Yesenia Obrien
Answered 2022-07-14 Author has 5 answers
sin 2 x + sin 2 2 x + sin 2 3 x = 1 ( 1 c o s 2 x ) + ( 1 cos 2 2 x ) + ( 1 c o s 2 3 x ) = 1
Rearranging terms we get cos 2 x + cos 2 2 x + cos 2 3 x = 2
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